U.S. patent number 7,025,845 [Application Number 10/247,300] was granted by the patent office on 2006-04-11 for surface mounted device type package using coaxial cable.
This patent grant is currently assigned to Samsung Electronics Co., Ltd.. Invention is credited to Ja-nam Ku, Il-jong Song.
United States Patent |
7,025,845 |
Song , et al. |
April 11, 2006 |
Surface mounted device type package using coaxial cable
Abstract
A surface mounted device (SMD) package using coaxial cables and
a method of manufacturing the SMD by forming green sheets and
selecting portions for mounting the coaxial cables on the green
sheets and forming holes in the portions selected, stacking and
heating the green sheets having the holes, and inserting the
coaxial cables into the holes of the green sheets. The SMD includes
a device mounting unit formed in the package for mounting a high
frequency electronic device which transmits and receives high
frequency signals, transmission lines electrically connected to the
high frequency electronic device, and the coaxial cables
penetrating internal and external portions of the package and
including internal lead wires which contact the transmission lines.
The SMD package is formed to conveniently transfer high frequency
signals without the signal transfer loss.
Inventors: |
Song; Il-jong (Suwon,
KR), Ku; Ja-nam (Suwon, KR) |
Assignee: |
Samsung Electronics Co., Ltd.
(Kyungki-do, KR)
|
Family
ID: |
19718644 |
Appl.
No.: |
10/247,300 |
Filed: |
September 20, 2002 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20030139070 A1 |
Jul 24, 2003 |
|
Foreign Application Priority Data
|
|
|
|
|
Jan 19, 2002 [KR] |
|
|
2002-3192 |
|
Current U.S.
Class: |
156/89.12 |
Current CPC
Class: |
H01L
23/66 (20130101); H01L 2223/6622 (20130101); H01L
2924/09701 (20130101); H01L 2924/0002 (20130101); H01L
2924/1903 (20130101); H05K 1/0243 (20130101); H01L
2223/6627 (20130101); H01L 2924/0002 (20130101); H01L
2924/00 (20130101) |
Current International
Class: |
H01F
41/04 (20060101) |
Field of
Search: |
;439/63 ;385/92
;29/600,830-43,850 ;333/204,206 ;174/250-1 ;156/89.12 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Gushi; Ross
Attorney, Agent or Firm: Sughrue Mion, PLLC
Claims
What is claimed is:
1. A method of manufacturing a surface mounted device package using
coaxial cables, comprising: forming green sheets; selecting
internal and external portions for mounting the coaxial cables on
the green sheets and forming holes in the portions selected so as
to connect the coaxial cables to an outside of the package at any
desired location; stacking and heating the green sheets having the
holes; and inserting the coaxial cables into the holes of the green
sheets.
2. The method according to claim 1, wherein the coaxial cables are
connected to transmission lines and are adapted to protrude from
any portion of the package.
3. The method according to claim 1, further comprising bonding the
package to a printed circuit board.
4. The method according to claim 1, wherein the coaxial cables
transmit and receive high frequency signals, and wherein the
coaxial cables comprise internal lead wires which contact
transmission lines.
5. The method according to claim 1, wherein the coaxial cables are
formed in a ball, and comprise exposed sections thereof on an
external surface of the surface mounted device package, thereby
performing bonding when attaching the coaxial cables to a printed
circuit board.
6. The method according to claim 1, wherein the coaxial cables are
formed in a flat lead, which is extended to an external surface of
the surface mounted device package.
7. A method of manufacturing a surface mounted device (SMD) package
using coaxial cables, comprising: forming green sheets; selecting
portions for mounting the coaxial cables penetrating internal and
external portions of the package, on the green sheets and forming
holes in the portions selected; inserting dielectric material and
conductive material into each hole on the green sheets; and
stacking and heating the green sheets.
8. The method according to claim 7, wherein the coaxial cables are
adapted to protrude to external portions of the package connected
to transmission lines at any portion of the package, and wherein
the coaxial cables protrude to the external portions of the package
in accordance with the selection made.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a surface mounted device (SMD)
type package using coaxial cables and, more particularly, to an SMD
type package using more than one coaxial cable for conveniently
transferring high frequency signals and for being easily attached
to a printed circuit board (PCB).
2. Description of the Related Art
A conventional optical module includes an optical device and a
package unit that is electrically connected to the optical device
and is used for protecting the optical device. The optical module
as a necessary component in an optical communication system,
operates as an electric signal to an optical signal (E/O) and to an
O/E converter. In detail, the optical module converts the electric
signal of a base station, which is an input into master equipment
of an optical repeating system, into an optical signal.
Subsequently, the optical signal is transferred to slave equipment
installed in an area where service is provided through optical
cables. There is an increasing demand for optical modules capable
of transmitting increasingly larger amounts of data at increasing
higher speed. However, the amount of data and speed of its transfer
are limited by structural problems of the package which protects
the optical device and transfers high frequency signals.
In order for the package of the module to be suitable for the
transmission of high frequency signals, it must meet the following
conditions: first, the structure has to be simple so that it's
members can be manually arranged and positioned at predetermined
positions respectively; second, the package has to be conveniently
bonded to a PCB to transfer the signals efficiently; third, the
package must have a sufficient thermal capacity for minimizing
thermal shock to the electronic device caused by internal and
external heat of the module; and fourth, automation has to be
achieved and a packaging cost, which is the most expensive part of
manufacturing the module, has to be low.
A butterfly-type package is commonly used in conventional optical
communication. However, the butterfly-type package is limited in
its ability to transfer high frequency signals, so various types of
alternative packages have been suggested. An example of an
alternative package is shown in FIG. 1. In this package, via holes
13 are formed on a package unit 12 for connecting signal transfer
lines. Namely, the package unit 12, which is formed of the via
holes 13 used for transferring signals and of a ball grid array
(BGA) 14 used for bonding the via holes 13 to a PCB, is mounted on
an optical device. In this case, the optical device includes a
silicon optical bench 11 on which optical components are mounted
and a laser diode driver for controlling the optical components.
Signals are transferred through the via holes 13, and the BGA
bonding is performed under the via holes 13.
The package shown in FIG. 1 has several strengths. The size of the
package can be reduced, and the package has a small amount of
parasitic capacitance due to very small contact points. Moreover,
unlike the butterfly-type package, the bonding is conveniently
performed by using the via holes regardless of the number of
contact points.
However, when the package using the via holes 13 as shown in FIG. 1
transfers high frequency signals, transfer loss occurs. For that
reason, the via holes should be formed to have a smaller diameter.
Moreover, the package has to have a sufficiently high thermal
capacity for protecting optical devices that are sensitive to
temperature. If the thermal capacity of the package is too low, the
device inside may fall into a thermal shock.
As described above, the thermal capacity of the package is reduced
when the via holes are formed to have a smaller diameter; thereby,
the package insufficiently protects the optical device inside.
Moreover, in the case of using the via holes, direct current (DC)
signals are smoothly transferred, but it is difficult to transfer
high frequency signals of higher than 40 GHz, which recently have
been demanded by the industry.
SUMMARY OF THE INVENTION
To solve the above-described problems, it is an aspect of the
present invention to provide a package with a sufficiently large
thermal capacity so as not to be sensitive to external heat, to
transfer high frequency signals without a transfer loss, and to be
used as various types of high frequency electronic device packages
including an optical module.
An apparatus consistent with the present invention relates to a
surface mounted device (SMD) type package using coaxial cables,
comprising a device mounting unit formed in the package for
mounting a high frequency electronic device which transmits and
receives high frequency signals, transmission lines electrically
connected to the high frequency electronic device mounting unit,
and the coaxial cables penetrating internal and external portions
of the package and including internal lead wires which contact the
transmission lines.
In this case, each of the coaxial cables includes the internal lead
wire, a dielectric material formed on the external circumference of
the internal lead wire, an external lead wire surrounding the
external circumference of the dielectric material for being
grounded to the inner surface of the package, and an insulator for
coating the external lead wire.
It is preferable that the coaxial cables expose the sections
thereof on the external surface of the package or extended to the
external surface of the package.
It is preferable that a high frequency electronic device, such as a
silicon optical bench, a surface acoustic wave (SAW) filter, a
microwave monolithic integrated circuit (MMIC), or a
hetero-junction bipolar transistor (HBT), is mounted to the high
frequency electronic device mounting unit.
To further solve the above-described problems, it is an aspect of
the present invention to provide a method of manufacturing an SMD
type package using coaxial cables, comprising the steps of forming
green sheets, selecting portions for mounting the coaxial cables on
the green sheets and forming holes in the selected portions,
stacking and heating the green sheets having the holes, and
inserting the coaxial cables into the holes of the green
sheets.
To further solve the above-described problems, another aspect of
the present invention is to provide a method of manufacturing an
SMD type package using coaxial cables, comprising the steps of
forming green sheets, selecting portions for mounting the coaxial
cables on the green sheets and forming holes in the selected
portions, inserting dielectric material and conductive material
into each hole on the green sheets, and stacking and heating the
green sheets.
BRIEF DESCRIPTION OF THE DRAWINGS
The above aspects and advantages of the present invention will
become more apparent by describing in detail an illustrative,
non-limiting embodiment thereof with reference to the accompanying
drawings, in which:
FIG. 1 illustrates a conventional package having via holes;
FIG. 2A illustrates a surface mounted device (SMD) type package
according to the present invention;
FIG. 2B is a perspective view illustrating a coaxial cable inserted
into the SMD type package according to the present invention;
FIG. 3A is an illustrative, non-limiting embodiment of a ball grid
array (BGA); and
FIG. 3B is an illustrative, non-limiting embodiment of a flat
lead.
FIGS. 4A and 4B are flow diagrams of a method for manufacturing a
surface mounted device (SMD) type package using an LTCC process
according to an illustrative, non-limiting embodiment of the
present invention.
DETAILED DESCRIPTION OF THE INVENTION
The present invention will now be described in detail by describing
illustrative, non-limiting embodiments thereof with reference to
the accompanying drawings. In the drawings, the same reference
characters denote the same elements. An optical module according to
the present invention includes an optical device and a package in
which coaxial cables are used as signal transfer lines.
The structure of a surface mounted device (SMD) type package 21
according to the present invention is illustrated in FIG. 2A. The
SMD type package 21 according to the present invention includes a
device mounting unit 22 on which optical devices of a flat circuit
board are located; transmission lines 23, which are electrically
connected with the optical devices; and coaxial cables 24 for
connecting the transmission lines to the outside.
The SMD type package 21 according to the present invention is
applicable to various devices using high frequency signals,
including optical devices which transmit and receive optical
signals. Accordingly, various types of high frequency transfer
devices can be mounted in the device mounting unit 22. In this
case, the SMD type package 21 according to the present invention
may be used for transferring signals and protecting devices such as
a silicon optical bench (SIOB), a surface acoustic wave (SAW)
filter, a microwave monolithic integrated circuit (MMIC), and a
hetero-junction bipolar transistor (HBT).
The coaxial cable is formed of an internal lead wire 25, a
dielectric material 26 used as an internal insulator, an external
lead wire 27, and a coating material 28 as shown in FIG. 2B. The
internal lead wire 25 of the coaxial cable is brought into contact
with the transmission line, and the external lead wire 27 is
connected to a ground conductor on one surface of a printed circuit
board (PCB) for being grounded. The coaxial cable may transfer both
analog and digital signals. Since the dielectric material 26 is
used as the internal insulator, transfer loss caused by
interference between the coaxial cables is reduced, thereby
transferring high frequency signals well.
FIGS. 3A and 3B illustrate rear views of the SMD type package
according to the present invention shown in FIG. 2A. In FIGS. 3A
and 3B, the SMD type package 21 according to the present invention
includes a coaxial cable 32 and, a transition line 33
FIG. 3A is an illustrative, non-limiting embodiment of a ball grid
array (BGA) SMD type package, and FIG. 3B is an illustrative,
non-limiting embodiment of a flat lead SMD type package. Unlike a
conventional butterfly-type package in which signal transfer lines
protrude from a side to the outside, in the SMD type package
according to the present invention, the coaxial cables connected to
the transmission lines can protrude from any part of the package,
due to the improved method of manufacturing the package. As
depicted in FIG. 3A, A Ball Grid Array is formed on the outer
surface of coaxial cables.
The SMD type package is precisely mounted on the PCB by a BGA
bonding or flip chip bonding, but not by soldering. The BGA bonding
is used for the BGA SMD type package shown in FIG. 3A, and the flip
chip bonding is used for the flat lead SMD type package shown in
FIG. 3B.
A method of manufacturing an SMD type package using coaxial cables
according to the present invention will now be described.
The SMD type package using coaxial cables according to the present
invention is manufactured by a low temperature co-fired ceramic
(LTCC) process. The LTCC process forms a substrate by
simultaneously heating ceramic and metal at a low temperature of
about 800 to 1000.degree. C. The process will be described in more
detail herein below.
Specifically, glass having a low melting point and ceramic are
mixed for forming a green sheet having an appropriate dielectric
constant, and a conductive paste formed of silver or copper is
printed and stacked on the green sheet so that the substrate is
formed. Then, inactive devices such as a capacitor, a resister, and
an inductor are installed in the substrate. Accordingly, a device
having high integration density, reduced size and weight, and high
reliability can be formed.
A method for applying the LTCC process to the present invention
will be described herein below with reference to FIGS. 4A and
4B.
FIGS. 4A (at step 41) and 4B illustrate forming green sheets. After
the green sheets are provided, portions for installing coaxial
cables are selected on these green sheets at step 42 depicted in
FIG 4A for forming holes on the chosen portions. In FIG 4B, this
step is depicted with the stack of green sheets obtaining holes.
FIGS. 4A (at step 431) and 4B further illustrates that a dielectric
material and a conductive material are inserted into each hole on
the green sheets. Next, as illustrated in FIGS. 4A (at step 432)
and 4B, the green sheets are heated to form coaxial cable
structures around the holes on these green sheets. Alternatively,
as depicted in FIGS. 4A (steps 441 and 442) and 4B, the green
sheets may first be heated and then have the coaxial cables
inserted into the formed holes. In this illustrative, non-limiting
embodiment, the green sheets are heated at the same temperature
used in the conventional LTCC process. If the green sheets are
heated at a temperature higher than the heating temperature in the
conventional LTCC process, then it is difficult to form the
conductive material in the coaxial cables.
According to the present invention, the SMT type package is formed
to conveniently transfer high frequency signals without signal
transfer loss. Moreover, since coaxial cables in the package are
used as the signal transferring lines, the package has a large
enough thermal capacity to be insensitive to the external
temperature. The SMD type package according to the present
invention is applied to various types of electronic devices
including a SAW filter, an MMIC, or an HBT.
The above and other features of the invention including various and
novel details of construction and combination of parts have been
particularly described with reference to the accompanying drawings
and pointed out in the claims. It will be understood that the
particular construction and combination of parts embodying the
invention is shown by way of illustration only and not as a
limitation of the invention. The principles and features of this
invention may be employed in varied and numerous embodiments
without departing from the scope of the invention.
* * * * *